插层Bi对NiFe/FeMn双层膜交换偏置场的影响及其XPS分析

The influence of Bi on the exchange bias field of NiFe/FeMn bilayers and the XPS analysis

在Ta/Cu/NiFe/FeMn/Ta薄膜中,我们曾发现Cu在NiFe层的表面偏聚导致NiFe/FeMn薄膜的交换偏置场降低。为了抑制Cu的表面偏聚,我们在Ta/Cu/NiFe/FeMn/Ta薄膜中在Cu/NiFe界面沉积Bi插层。实验发现,沉积适当厚度的Bi插层可以将NiFe/FeMn双层膜的交换偏置场提高1倍。XPS分析表明,在Cu/NiFe界面沉积的插层Bi有效地抑制了Cu在NiFe表面的偏聚,提高了交换偏置场。

Experimental results show that Cu atoms can segregate to the NiFe surface in Ta/Cu/NiFe/FeMn/Ta films. This segregation results in a decrease of the exchange bias field （Hex） of NiFe/FeMn. In order to sup- press the Cu surface segregation, we deposited Bi insetting layers at the interface of Cu and NiFe in Ta/Cu/ NiFe/FeMn/Ta films. We found that the Hex of NiFe/FeMn can be doubled when the proper Bi was deposited. XPS analysis shows that Bi insetting layers deposited at the interface of Cu/NiFe effectively suppress the Cu segregation on the NiFe surface. As a result, the Hex was increased.